Gravesenvognsen2625

A graphene-embedded plasmonic rib waveguide (GEPRW) is designed for the mid-infrared electro-optic modulator. The mode characteristics and electro-optic (EO) modulation performances are simulated and optimized by using the finite element method. The results show that propagation length of 103mm and figure of merit of 106 are obtained by adjusting the bias voltage applied to the GEPRW. The EO wavelength tunings are -66.69 and -78.87nm/V for peak L and peak R in the loss spectra when w=3µm and h1=2µm. For a 100 µm long GEPRW, the modulation depths of ∼96.4,∼97.1,∼93.7, and ∼94.9%, and FWHMs of ∼30,∼74,∼34, and ∼59nm can be achieved when λ=1.55, 1.87. read more 1.89, and 2.23 µm. The EO modulator based on the GEPRW has a wide wavelength tuning range from 1.05 to 2.23 µm. It has high modulation depth, low insertion loss, and broad bandwidth, which can be used as EO tunable devices such as optical interconnects and optical switches.The Doppler effect of motional polarization grating is studied for the first time to the best of our knowledge. Based on the optical properties of polarization grating, the Doppler effect principle of polarization grating is elucidated theoretically. A method to obtain the Doppler frequency shift based on beat frequency signal that is produced by superposition of order ±1 diffraction beams of polarization grating is proposed, and a proof-of-concept experiment is conducted to measure the frequency signal of the motional polarization grating. The movement characteristics of polarization grating varying with time can be obtained after a short-time Fourier transformation of the light signal. The experimental results are in good agreement with the theoretical predication, which verifies the correctness of the theoretical analysis and achieves the measurement of linear motion velocity and acceleration of motional polarization grating with high accuracy. This study proposes a new idea for laser frequency shift and has potential significance for further development of optical heterodyne detection.Improving photothermal efficiency can reduce the melting threshold of metal nanowires. The photothermal efficiency of a polarized laser to Cu nanowires was investigated by numerical simulation and experiment. Our simulation results reveal that the photothermal efficiency of a polarized laser depends on the intensity and distribution area of surface plasmons excited by the laser. As the angle between the polarization direction of the incident laser and the long axis of the Cu nanowire increases, the laser-excited surface plasmons shift from both ends to the sidewall of the Cu nanowire. Such a distribution of surface plasmons was confirmed by the melting behavior of Cu nanowires irradiated by a 450 nm polarized laser. Increasing the laser wavelength will enhance the intensity of the surface plasmons but reduce the distribution area of the surface plasmons. As a result, a higher photothermal efficiency was achieved using a laser with a polarization direction perpendicular to the long axis of the Cu nanowire and a wavelength less than 550 nm. Due to the higher photothermal efficiency, the melting threshold of Cu nanowire irradiated by a laser with polarization perpendicular to the long axis of the Cu nanowire is 32 mW, which is around 20% lower that of Cu nanowire irradiated by a laser with polarization parallel to the long axis of the Cu nanowire.Indoor visible light communication (VLC) systems with narrow beams can achieve practical few-meters-long wireless optical links. Such links can operate at low power levels and high data rate for supporting point-to-point or multipoint communication. The narrow-beam VLC links can, however, benefit from beam steering to support mobility of user equipment and cater to multiple users. Simple beam-steering techniques with minimal changes to the existing optical hardware are required to enable widespread adoption of beam steering in VLC links. We study the performance of a simple transmitter-lens-decenter-based beam-steering scheme in a VLC link, utilizing a phosphor down-converted blue laser transmitter. The beam-steering angle and hence the receiver coverage depend on the transmitter lens decenter and the choice of the transmitter and receiver lens's focal lengths. Optical ray tracing is used to quantify the collection efficiency achievable with beam steering, choose a suitable receiver lens, and understand the role of off-axis aberration in the system performance. In our experimental implementation, the transmitter lens decentering technique results in a maximum steering angle of 7.1°. This corresponds to a receiver coverage of 30 cm per cm of transmitter lens decenter for a fixed link length of 300 cm. The measured on-axis white light color coordinates of (0.286, 0.253) is found to shift toward warmer white colors with beam steering. The on-axis illuminance level of ∼19lux decreases slightly with beam steering and is found to be below the maximum permissible exposure limit for indoor illumination. We also quantify the data communication performance as a function of beam steering using on-off modulated data. Bit-error rates below the forward error correction limit are obtained for receiver coverage diameter of 75 cm and 60 cm for 1.25 Gbps and 1.5 Gbps data rates, respectively.To improve grating manufacturing process controllability in scanning beam interference lithography (SBIL), a novel method for exposure dose monitoring and control is proposed. Several zones in a narrow monitoring region are fabricated on a grating substrate by piecewise uniform scanning. Two monitoring modes are given based on the different widths of the monitoring region. The monitoring curve of the latent image diffraction efficiency to scanning velocity is calculated by rigorous coupled wave analysis. The calculation results show that the exposure dose in SBIL can be monitored by the shape change of the monitoring curve, and an optimized scanning velocity can be selected in the monitoring curve to control the exposure dose.In a resonator micro-optic gyroscope (R-MOG), backscattering noise and Kerr noise have been key issues affecting the optical gyro output that are difficult to completely suppress. A method is proposed to suppress backscattering noise in a R-MOG. It uses two independent lasers and, by locking the two optical signals at different resonance peaks, a differential output of the two optical signals is achieved that successfully suppresses the backscattering noise. At the same time, a light intensity feedback loop based on a light intensity modulator is added to the loop to ensure the same optical power into the cavity. Experimental results show that the light intensity fluctuation into the gyro system is reduced nearly two orders of magnitude and the bias stability is improved to 9.06 deg/h by using a light intensity feedback loop with two independent lasers.